Method and reactants for modifying cellulose polymers



US. Cl. 260-212 29 Claims ABSTRACT OF THE DISCLOSURE Cellulosic polymers are' modified by reaction with an organic reactant having at least one cellulosic reactive group such as an aldehyde radical or an N-methylol amide radical and a sulfur containing radical such as mercapto, protected mercapto or disulfide. The resulting product is reversibly cross-linkable by the formation and cleavage of disulfide groups. In addition, the presence of free mercapto groups facilitates further modification of cellulosic polymers by alkylation.

DISCLOSURE This application is a continuation-in-part of application Ser. No. 347,365, filed Feb. 26, 1964, now abandoned.

This invention relates to a method of modifying cellulosic polymers and more particularly to a method of modifying a material comprising cellulosic polymers. The invention also relates to organic reactants which are suitable for treating cellulosic polymers in accordance with the method of the present invention.

Wool fibers consist primarily of long chain polymers which are crosslinked by disulfide radicals. These disulfide crosslinks impart certain useful properties to the wool fibers. Thus, for example the disulfide crosslinks can be opened, the fibers may be' given a desired configuration, and the crosslinks then reformed in order to stabilize the fibers in their new configuration. Permanent creasing of wool fabrics is one important commercial utilization of the naturally occurring disulfide linkages.

In view of the widely accepted importance of disulfide crosslinks in imparting desirable properties to wool fibers, it is apparent that the introduction of such crosslinks into cellulosic polymers is a desirable objective. The disulfidemercaptan system is especially desirable due to the ease of conversion of one form to the other.

In addition to the advantages resulting from the reversibility of the disulfide-mercaptan linkage, the modification of cellulosic polymers by introduction of this system is important for another reason. The reactivity of cellulosic polymers is somewhat limited since the hydroxyl groups provide the only reactive sites. Since mercapto groups are much more reactive than hydroxyl groups in many organic reactions, the introduction of mercapto groups into cellulosic polymers increases the reactivity of the cellulose in organic reactions such as alkylation and graft polymerization.

In view of the foregoing, it is an object of the present invention to provide a method of modifying a material comprising cellulosic polymer molecules by introducing disulfide or mercapto radicals into the cellulosic polymer molecules.

It is another object of this invention to provide organic reactants including a mercapto radical or a disulfide radical for use in treating cellulosic polymer molecules in accordance with the method of this invention.

Briefly stated, one embodiment of the present invention is the method of modifying a material comprising nited States Patent 0 "ice cellulosic polymer molecules comprising the steps of providing an organic reactant embodying (A) a cellulosereactive group, such as formyl (--CHO), or an N-methylol carbamoyl radical or ether derivatives thereof having the formula:

wherein R and R" are hydrogen or substituted or unsubstituted hydrocarbyl, such as substituted or unsubstituted alkyl of from 1 to 4 carbon atoms; and (B) a sulfur-containing group such as a disulfide radical or a mercapto radical in a free or protected form, as acylthio; said cellulose-reactive group and said sulfur-containing group being separated by a divalent organic linking radical containing at least one intralinear carbon; and treating said material with said organic reactant in the presence of an acidic catalyst.

The organic reactants can be represented by the general formula:

wherein Z is said cellulose-reactive group; T is said linking radical; X is mercapto or protected mercapto, e.g., acylthio, or a disulfide group; and n is an integer having a value of 1 when X is free or protected mercapto and a value of 2 when X is disulfide. When n in Formula I has a value of 2, the ZT-groups may be the same or different.

As noted above, the cellulose-reactive group can be formyl. Alternatively it may be a group which, under the reaction conditions (i.e., in an acidic medium) yields a formyl radical, such as an aldehyde acetal group of the formula:

wherein R is substituted or unsubstituted hydrocarbyl, such as substituted or unsubstituted alkyl having 1 to 4 carbon atoms. Compounds having the aldehyde acetal grouping, when subjected to the conditions hereinafter described for the treatment of cellulose, form the formyl group which then reacts with the cellulose. This conversion of acetal to aldehyde is illustrated by the following equation, employing a mercapto acetal for purpose of illustration:

reducing Thus, if a mercapto type of reactant is used to form disulfide crosslinks in accordance with the present method, only one cellulose-reactive functional group need be present in the reagent molecule. The crosslink between cellulosic polymers in such instance is formed by reaction of two mercapto-containing chains to form a disulfide linkage.

When employing the mercapto type of reactant it is frequently desirable to have the mercapto group in a protected form to prevent premature disulfide formation by oxidation due to atmospheric oxygen which may be present during preparation of the reactant, or during treatment of cellulose. A suitable protective form of the mercapto group is the acylthio group of the formula:

S(DR (IV) wherein R' is substituted or unsubstituted hydrocarbyl such as substituted or unsubstituted alkyl or acyl having from 1 to 10 carbon atoms.

The acylthio group is unaffected by the acidic media employed during the reaction of the organic reactant with cellulose, but the acyl protecting group may be readily removed (i.e., the acylthio group is converted to mercapto), by treatment with base.

If a disulfide-containing rasctant is used to form disulfide crosslinks, there must be two cellulose-reactive functional groups present. The crosslink in this case is formed by reaction of one cellulose-reactive functional group with a first cellulosic polymer molecule, and reaction of the second group with a second collulosic polymer molecule.

The cellulose-reactive functional group must be separated from the sulfur-containing radical by at least one carbon atom to prevent splitting of the compound at this juncture. Preferably, the cellulose-reactive functional group should be separated from the sulfur-containing radical by a substituted or unsubstituted alkylene radical having from 1 to 4 carbon atoms.

Substituents which may be present on the various groups defined above include any substituent which is inert under the reaction conditions. Particularly desirable substituents are those wherein oxygen is present in the form of a hydroxyl group or an ether linkage, which improve the solubility of the organic reactant in water and make them more attractive for commercial utilization.

Some typical examples of organic reactants which are suitable for the practice of this invention are as follows:

Although most of the above compounds are of the disulfide type, it is to be appreciated that the mercapto form corresponding to the disulfide compounds may be formed by reduction, and these mercapto compounds are considered included in the foregoing illustrative list.

Compounds (1)-(6) contain the N-methylol amide or ether derivatives thereof type of cellulose-reactive functional group; compounds (7) and (8) contain the aldehyde acetal type of group; and compounds (9) and (10) contain the aldehyde type of group.

In compounds (3) and (10) the cellulose-reactive functional groups are separated from the sulfur-containing groups by a radical containing an ether linkage. ln compounds (4) and (9) there is a hydroxyl substituent.

Each of the disulfides discussed above is symmetricalthat is, the portions of the molecule on either side of the sulfur atoms are identical. The present invention is intended to cover unsymmetrical disulfides as well, and these may be made, for example, by mild oxidation or a mixture of two mercapto compounds.

Typical temporarily protected forms of the thiols which may be used as organic reactants in the practice of this invention are as follows:

(11) HOCHzNPJCHzSCH;

( 021150 CH2N( 3 CHS( J OflH5 H CH 0 3) CiHgO CHzN CHSg C H 14) (CfigohCHCHzs CHa O H CHS C Sulfur-containing compounds of the N-rnethylol amide type can be prepared by conventional techniques. The preparation of one such compound (Compound 1) is illustrated as follows:

Example 1 First an intermediate having the following formula was prepared:

To this end 64 grams of sulfur were added at room temperature to 240 grams of Na S-9H O dissolved in 2000 ml. of water while stirring. This mixture was warmed up to 70 C. and kept at this temperature until the sulfur went into solution. Then the solution was cooled to room temperature and 284 grams (4 moles) of acrylamide dissolved in 400 ml. water were allowed to drip into this solution over a period of 30 minutes. The reaction was slightly exothermic. After half of the acrylamide solution was added, a crystalline product started to precipitate. After the addition of acrylamide was completed, the reaction mixture was stirred for additional 30 minutes. then filtered. The crude product was washed with water. dried and recrystallized from 4500 ml. ethanol. The

Weight of recrystallized product was 195 grams, corresponding to a 47% yield.

The melting point of the product Was 160 C.162 C., the sulfur content was 31.03 by weight and the nitrogen content 13.09% by weight. The theoretical sulfur content of the above intermediate is 30.80% and the theoretical nitrogen content is 13.45%.

In the second part of this procedure 156 grams (0.75 mole) of the intermediate was slurried in 1900 ml. of water. The pH of the aqueous slurry was adjusted to 8.0- 8.2 by adding a few drops of 5 N NaOH. The aqueous slurry was heated to 65 C. with stirring. A clear solution was obtained. 123 grams of 37% aqueous formaldehyde solution (1.5 moles) were allowed to drip into this solution over a period of 1 hour. After stirring for hours, 73% conversion (determined from the decrease in free formaldehyde content of the reaction mixture by using hydroxylamine hydrochloride) Was achieved. By partially distilling off the water under reduced pressure, the reaction mixture was concentrated to 300 grams.

After chilling in the refrigerator overnight, 1800 m1. methyl ethyl ketone were added. A white crystalline product was obtained and filtered. It was recrystallized from 98 grams corresponding to a 48.5% yield. M.P.:

129132 C. The product was slightly soluble in water II H2No( )-SS( )C 2 [Where W is defined as in Formula II] to the corresponding bis- (N-methylol) amides:

In the presence of excess alcohol [ROH, where R is defined as in Formula I] and by suitable changes in the solution pH during the reaction with formaldehyde, the corresponding bis-alkoxymethyl amides:

RI! R [where R and W are defined as above] are used as the intermediates, the reaction with formaldehyde will occur on the free hydrogen and the corresponding N-substituted reactants will be obtained.

The intermediate dithioamides required for the preparation of the new reactants can be prepared from the corresponding unsaturated compounds as shown in Example l, or by converting a haloamide to a mercaptan, for example:

or by reacting a sulfur containing acid chloride with ammonia or an amine, for example:

Preparation of a preferred temporarily protected reactant, 2-(acetylthio)-N-(hydroxymethyl) acetamide is illustrated by the following example:

- (theoretically 302 grams). Ethanol was evaporated from the filtrate, leaving 662 grams of solid (theoretically 660 grams) of 2-(acetylthio)-N-(hydroxymethyl) acetamide, which upon being recrystallized from ethyl acetate in 72% yield, melted at 93 to 965 C. (104 to 105 C. after recrystallization from benzene.) Analysis of bound formaldehyde indicated a purity of 96.2% (17.7% found compared with 18.4% required for C H NO S). Absorption bands in the infrared spectrum were those expected for the structure shown above.

This procedure is not limited to thiol S-esters of N- (hydroxymethyl) amides, but can be applied generally to aldehydes, acetals, or N-(oxymethyl) alkanarnides which have a halogen atom (chlorine, bromine or iodine) bonded to the carbon atom which ultimately is to hold a mercapto group or a dithio group. An alkali metal salt of a thiocarboxylic acid is used to effect a replacement reaction. Thus, the acetylthio group can be provided by potassium thioacetate and the benzoylthio group can be provided by sodium thiobenzoate.

In general, the organic reactants of this invention are utilized in a solvent, preferably water. Assuming the material to be modified is a cotton fabric, a solution of one of the organic reactants is applied to the fabric by dipping, spraying, padding or other suitable manner. The process requires acidic conditions, or in other words, the presence of an excess of hydrogen ions. It is believed that the reaction of the aldehyde type of compound with a cellulosic polymer molecule is as follows:

The treatment of cellulosic polymer molecule with compounds including an N-methylol amide radical proceeds generally as follows:

Although the solvent utilized to form the solution of the sulfur-containing reactant is preferably water, when the solubilities of the reactants in water are not sufiicient for the desired purposes, the water may be mixed with a compatible organic solvent, or an organic solvent alone may be used.

The amount of the sulfur-containing reactant to be applied to the cellulosic material generally should be in the range of from 2% to 30%, based on the weight of the cellulosic polymer molecules in the material being treated. Of course, the particular strength which is selected will be based on the extent of modification which is required for the particular properties which are desired. It has been determined that the use of from 5% to of sulfur-containing reactant, based on the weight of the cellulosic polymer molecules, is suflicient to impart excellent properties.

As indicated, the treatment of cellulosic polymer molecules with the sulfur-containing reactants of this invention must be conducted under acidic conditions. Acidic catalysts which are suitable for use with the present invention include the ammonium salts of mineral acids such as hydrochloric, sulfuric, phosphoric, perchloric and nitric; amine salts of mineral acids; the chlorides and nitrates of zinc and magnesium; acid fluoride salts; zinc fiuoroborate and others of this type. In addition to the above salts, non-volatile acids of moderate strength such as oxalic acid and sodium hydrogen sulfate may also be employed.

Some of the above acidic catalysts, such as magnesium chloride are acid-forming and provide acidic conditions upon heating. When such catalysts are used, the treated material must be heated to the temperature level necessary for production of the requisite acid conditions.

If the acidic catalyst is of the type that does not require heating to form hydrogen ions, for example, those catalysts which form hydrogen ions upon hydrolysis or ionization in a solvent, the catalytic activity is generally controlled by appropriate choice of the pH of the treating solution. In such instance, the pH of the treating solution should be higher than about 3.5 since the use of acid catalysts yielding a substantially lower pH may adversely affect the cellulosic material being treated.

The term acidic catalyst as used in this specification and in the claims appended hereto is intended to include those substances which are acidic per se as well as those compounds or materials which have the latent ability to provide acidic conditions in situ, for example, by exposure to elevated temperature.

After treatment with the organic reactant and catalyst, the treated cellulose is generally dried at a relatively low temperature and then heated to a higher temperature for a short period of time to accelerate the reaction between the cellulose and the sulfur-containing reactant. Preferably, the higher temperature step is conducted at temperatures in the range of 140 C. to 175 C. for a time in the range of about 2 minutes to 10 minutes. Of course, temperatures lower than 140 C. may be used with a corresponding increase in the time.

The term cellulosic polymer molecule as used herein is intended to denote the cellulose polymer molecules as they occur naturally in the form of cotton, linen and wood. It is also intended to embrace modified cellulose such as regenerated cellulose including viscose, cuprammonium rayon and saponified cellulose acetate, cellulose film; soluble modified cellulose such as hydroxyethyl cellulose and carboxymethyl cellulose; and the like provided the modified polymer molecules contain free hydroxyl groups. The cellulose can be in the form of textile fibers which have been manufactured into fabric, or in the form of films, fibers or yarns. Cellulose fibers may be incorporated into yarns and fabrics together with other textile fibers, and the composite material may be treated by the present process. In addition, such natural cellulosic materials as wood and linen may also be treated in accordance with the present invention.

Cellulose which has been treated in accordance with this invention is reversibly cross-linkable whereby disulfide linkages can be cleaved by reduction (incorporation of hydrogen) and reformed by oxidation (abstraction of hydrogen). When the modified cellulosic material is in the reduced or mercapto form the material may be creased or otherwise shaped and then exposed to a mild oxidizing treatment to restore the disulfide crosslinks.

Oxidizing agents for forming disulfide crosslinks in the complex cellulosic polymers containing mercapto groups include hydrogen peroxide, sodium perborate, gaseous oxygen with anhydrous ferric sulfate in dimethyl sulfoxide [C. G. Overberger et al., J. Am. Chem. Soc., vol. 87, 4125-4130 (1965)], and atmospheric oxygen, as well as iodine [R. F. Schwenker et al., Textile Res. 1., vol. 32, 797-804 (1962), and Vol. 33, 107-117 (1963)].

Reducing agents for rupturing disulfide crosslinks and forming mercapto groups include alkali and ammonium salts of aliphatic mercaptans such as thioglycolic acid, thioglycerol, mercaptoethanol and the like, neutralized tetrakis (hydroxymethyl) phosphonium chloride, sodium hydrogen sulfide with sodium sulfite, tributylphosphine, sodium tetrahydroborate and water, and 1,4-dimerceptothreo2,3-butanediol.

In addition, disulfide cleavage may result from simultaneous reduction and oxidation (disproportionation by a base).

The mercapto form of cellulosic derivatives produced by the methods of this invention can be further modified to new and useful compositions by alkylation in any of several ways. One such method is by reaction with activated vinyl compounds, such as acrylonitrile, divinyl .sulfone and N-ethylmaleimide. Another is by metathesis,

a replacement reaction which involves treating the mercapto-containing polymer with strong base such as sodium hydroxide, to make the S-sodium derivative, followed by reaction with a halogen-containing compound. For instance, iodoalkanes require about 6 hours at 50 C. when used as a 5% by weight solution in dimethylformamide free of molecular oxygen. Such a replacement reaction is not confined to haloalkanes, and iodoacetamide, bromoacetaldehyde acetals, and chloroacetonitrile are examples of other compounds which are suitable.

Whether formed by addition or replacement, the resulting organic sulfides are stable derivatives, sulfur analogues of ethers). In this manner one can provide modified forms of cellulose in a more facile fashion than by previous techniques or provide forms heretofore unattainable because of the higher reactivity of the mercapto groups as compared with cellulosic hydroxyl groups.

The following examples are illustrative of the methods by which cellulose may be modified in accordance with this invention. In these examples, the following test methods and analytical procedures were employed:

1) Crease recovery-Monsanto Test Method ASTM D-1295-60T, October 1961. Reported as the sum of the crease recovery angles in the warp and filling directions (W-l-F) after one laundering according to AATCC 88- 1961T, Test III C-2.

(2) Tear strength.Elmendorf Method ASTM D- 1424-59, Reported in pounds.

(3) Tensile breaking strength.-One-inch ravelled strip method; ASTM D-1682 59T. Reported in pounds.

(4) Moisture regain.Moisture gained on conditioning (relative humidity 65i2% at 21:1" C.) based on the oven-dry weight; ASTM D-629 59T. Reported in percent.

() Efficiency of utilization of reagent (in percent) (equiv. Wt. of reagent) (observed wt. gain) (100%) (equiv. wt. of group of atoms becomin g bonded to po y Table I.

TABLE I Reagent, Moisture Weight S, Percent N, Percent percent regain, gain,

WF percent percent 1 Calcd. Found (Jalcd. Found 1 Corrected for change in moisture regain. 2 Calculated from the corrected weight gain for the cellulose derivative, CellO CHZNHCOCHQSCOCHQ.

(6) Thiol sulfur.-The sample (approximately 0.08 gram) was kept for 511 days at room temperature in 100 ml. of solution containing 0.0125 gram of N-ethylmaleimide.

clzHs O=(f3N(I3=O HC=CH bulfered at pH 3.5. Its reaction with thiol groups was determined quantitatively from the change in ultraviolet absorbance at 300 millimicrons, as described by ,R. W. Burley and F. W. A. Horden, Textile Res. 1., vol. 27, 615-622 (1957).

(7) Disulfide sulfur.The sample (approximately 0.24 gram) was kept for 24 hours in 25 ml. of nitrogenfiushed water containing 0.020 gram of 1,4-dimercaptothreo-2,3-butanediol Total (W-l-F) crease recovery Warp Warp recovery angle, degrees tensile tear strength, strength, Dry Wet pounds pound Sample Example 4 Samples of fabric resulting from treatment similar to that described in Example 3 were treated under nitrogen with 0.2-normal sodium hydroxide solution at a fabricto-liquor weight ratio of 1-to-30 for 30 minutes at room temperature. Then they were washed thoroughly in succession with water, aqueous 2% acetic acid, again with water, and finally dried. Samples were kept under nitrogen until physical testing and analyses were performed. The

(3332311 test results are summarized in Table II as Sample A, to- H0011 gether with similar data obtained on (B) a fabric sample H OH resulting from treatment similar to that described in Example 3 so that the nitrogen content was 1.05%, and (C) HZSH 49 an untreated specimen of the printcloth.

TABLE II crease recovery Warp angel, degrees tens. Thio str., S, Sample Form Dry Wet lb. percent percent A Thiol 174 23s 39 1.0 1.85 B S-ester 259 246 39 1.05 0.25 o Untreated 182 172 56 0 0 The amount of odithiane-4,5-diol Example 5 C H2S Example 3 Samples of de-sized, bleached, and un-mercerized plainweave cotton fabric (commonly known as 80 x 80 print- Samples of fabric comprising (2-mercaptoacetamido)- 0 methylcellulose produced as described in Example 4 were treated with a neutral, aqueous 3% solution of hydrogen peroxide, with the fabric-to-liquor ratio at 1-to-30 by weight, for 30 minutes at room temperature. Then they were washed with water and dried. The resulting product comprised cellulose crosslinked through CH NHCOCH SSCH CONHCH groups which had total (warp plus filling) crease recovery angles of 242 degrees (dry) and 265 degrees (wet), a Warp tensile strength of 37 pounds, 0.9% N, and 0.0% thiol sulfur.

Example 6 Samples of fabric comprising (2-mercaptocetamido)- methylcelluloses produced as described in Example 4 were extracted repeatedly with dimethyl sulfoxide to replace water. Then they were treated at room temperature for 30 minutes with a 0.1% solution of anhydrous ferric sulfate in dimethyl sulfoxide through which a vigorous ide to re-form the crosslinks. The cycle of cross-link cleavage and reformation was repeated. The data for this series of experiments are summarized in Table V, with sample A being that produced in Example 5.

TABLE V W+F cr. recovery Warp angle, deg. tens. Thioi Distinguishing str. vi Sample composition Dry Wet lb. percent percent A- Cross-linked 242 265 37 0.95 .1.0 B Thiol 193 255 V 35 1. 0. 47 233 269 32 0.9 0. 189 254 31 0. 8 0. 21 E Cross-linked 233 269 29 1. 0 t). 07

stream of oxygen was passed. The fabric-to-liquor ratio- Example 9 was 1-to-30. At the end of the 30-minute oxidation, the samples were washed with water and dried. Data showing the history of the sample at each of the S-ester (A), the thiol (B) and the crosslinked stages are summarized in Table III.

TABLE III W-l-F er. recovery Warp S angle, deg. tens.

str., Total, 'Ihlol, -SS-, Dry Wet lb Percent Percent Percent Percent 260 249 2. 48 None 0. 08 Thiol 192 229 2. 1. 14 None Cross-1inked- 284 264 2. 28 0. 01 1. 26

Example 7 Samples of fabric comprising (2-mercaptoacetamido)- methyl-cellulose produced as described in Example 4 were exposed to air at 211-2% for periods of up to 10 weeks. The data for this series of experiments are summarized in Table IV.

TABLE IV W+F dry crease Sulfur content Period recovery of time, angle, Thiol, SS, Sample weeks degrees percent percent 1 The relative humidity of the air was i2%.

having 0.5 mole of sodium hydrogen sulfide and 0.5 mole of sodium sulfite per liter. In order to effect the exchange of hydrogen atoms between reactants, the sample was heated in steam for 10 minutes. The accompanying Table VI records the data on the modified cellulose in fabric form from preparation of the S-ester (A); formation of the thiol fonn (B); crosslinking according to Example 5 (C) and as it was carried through three cycles of reduction (acceptance of hydrogen atoms) and oxidation (dehydrogenation to form disulfide crosslinks) (D-I).

Example 8 Samples of fabric containing dithiobis(acetamidomethyl)crosslinks produced as described in Example 5 were treated under nitrogen with an aqueous 20% solution of tetrakis(hydroxymethyl)phosphonium chloride adjusted to pH 7.0 with sodium hydroxide, with the fabric-to-liquor ratio at 1-to-30 by weight, for 2 hours at 40 C. Then the samples were washed with water and dried. The resulting thiol form was then treated with hydrogen perox- A sample of fabric identical with sample C of Example 9 was immersed for 2 hours at 40 C. in an aqueous solution containing 0.5 mole of tributylphosphine per liter to cleave the disulfide cross-links. This sample (D) was then cross-linked with hydrogen peroxide as described in Example 5 (sample E). Two additional cycles of cleavage with tributylphosphine and oxidation with hydrogen peroxide were performed (F-I). The results of these experiments are summarized in Table VII.

TABLE VII W-i-F or. recovery angle, deg.

Dry Wet Example 11 Acrylonitrile-modified products of this nature are heatresistant and rot-resistant.

Example 13 The procedure of Example 12 was repeated, except that divinyl sulfone was used instead of acrylonitrile. Starting with sample D of Example 12, data on the history and properties of the modified fabric are summarized in Table X. The increased percentage of sulfur upon treatment with divinyl sulfone indicated that chemical addition occurred.

1 This percentage of thiol sulfur was calculated from the increase in percentage of sulfur (the addition of divmyl sulione was not quantitative).

The results of these experiments are summarized in Table VH1.

TABLE VIII W+F er. recovery angle, Warp deg. teps.

Sample Form Dry Wet lb. percent percent 267 279 201 235 23s 25s 1s1 233 219 250 170 23s 228 246 Example 12. Example 14 A Sample f containing dithiobis(acetamid' A sample of fabric characterized by containing the CIOSShHkS mtrodueed the method of EXaIiUple S a ety1 derivative of (2 mercaptoacetamido)methyl- 5 and subsequently reconverted to (2-mercaptoacetam1do) cellulose was prepared by a method similar to that methylceuulose y the metllod 0f Exqmple 9 wasvPadded described in Example 3. The fabric so treated had the with an aqueous 1% solut1on of sod1um hydroxide, and f ll i Io erties;

EP P Without drymg, the padded fabric was lmmersed 1n acrylonitrile for 30 minutes at room temperature. At the end N perccnt-.. 1.30 of the period of time allowed for the addition reaction, S r1n 2,48 the fabric was rinsed in water, next in dilute acetic acid, Thiol S None then thoroughly in water, and finally dried. Data show- Disulfide S None ing the history and properties of the modified fabric are Crease recovery: summarized in the accompanying Table 1X. The in Dry degrees 247 creased percentage of nitrogen upon treatment with acry- Wet do 237 lonitrile indicated that chemical addition occurred. Warp tensile strength pounds 41 TABLE IX W+F crease recovery Total angle, degrees N Thiol Sample Form Dry Wet percent percent percent 244 245 0. 74 1. 4 Trace 203 Unanalyzed 1. 4 227 276 Unanalyzed Trace 180 22s 0. so 1. 4 1. 4 206 257 1.16 1. 4 1 o. 99

(the addition of acrylonitrile was not quantitative).

Then, by using a procedure similar to that described in Example 4, the S-acetyl group was replaced by hydrogen, leaving free (Z-mercaptoacetamido)methylcellulose. The sample was stored briefly in an atmosphere of dry nitrogen, and then padded with an aqueous solution of sodium hydroxide to form the S-sodium derivative. The thus treated fabric was immersed for 6 hrs. at 50 C. in a solution consisting of 5 parts by weight of iodoethane and 95 parts by weight of dimethylformamide. During the 6-hour period, nitrogen was bubbled through the reaction mixture. At the end of the reaction period, the

16 form resulted from the l-iodoalkanes, respectively, as listed in the heading: [2-(isobutylthio)acetamido]methylcellulose, [2- (pentylthio) acetamido] methylcellulose, [Z-(dodecylthio) acetamido] methylcellulose, and [2-(octadecylthio)acetamido]methylcellulose.

gen peroxide as described in Example 5.

TABLE XII Before treatment with H 02 W+F Warp er. recovery Wt. Thiol Tensile angle, deg. gain, S, str., Sample S-Alkyl percent percent lb. Dry Wet CH OH(CH3)2 0.8 None 28 211 1:34 -(CH2)(C 1. 7 None 218 .259 (CHzl9CH3 4.3 None 35 230 228 (CH2)11CH3 8. 3 0. 06 36 213 .324

After treatment with H202 W+F Di- Warp or. recovery sulfide Thigl tensile angle, deg. str. S-Alkyl percent percent lb: Dry Wet CH2CH(CHa)z 0. 17 None 36 213 155 -(CH2)4CH3 0. 10 None 35 224 .262 (CH2)9CH3. 0. 12 None 37 229 .158 D (CH2)17CH;; 0. 18 None 30 226 1: 1

fabric sample was rinsed in dimethylformamide and water, then desiccated in dry gaseous nitrogen. The resulting S-ethyl derivative was then treated with hydrogen Example 16 peroxide by the procedure of Example 5. Data relating to. this sample are summarized in the accompanying Table XI, together with data on the thiol form, both before and after treatment with hydrogen peroxide.

TABLE XI The fabric sample in the thiol form of Example i4 disulfide cross-links was subjected to treatment similar to that described in Example 8 to re-form the thiol groups. That is, the chemical reactions of Example 8 Thiol s'ethyl were applied to the crosslinked or disulfide form to yield Before treatment with H 02: (Z-mercaptoacetamido)methylcellulose by a route differf fi fi fgfig ggff f 3 35: ent from that used for the starting material of Examples Warp tensile strength, lb 39 36 14 and 15. The S-alkylat1on procedures of Examples 14 Crease rewvery' 206 206 and 15 were then applied to produce [2-(ethylthio)acet- 264 25 amido]methylcellulose listed in Example 15. Data relat- 80 12 ing to the various samples are summarized in Table XIII, N023 01 which includes data on a series of five corresponding sam- Crease recovery: ples subsequently treated with hydrogen peroxide as de- D degrees 257 203 scribed in Example 5. Wet, degrees 278 233 TABLE XIII Before treatment with H109 After treatment with H1O,

W+F Or.recoveryl W+F Cr. recovery Warp angle, degree Warp angle, degree Thiol S, tensile Disulfide S, Throl S, tensile Sample S-Alkyl Wt. gain, str., lb. Dry Wet Percent Percent str., lb. Dry Wet; 1. 41 38 193 260 0. s4 0. 41 37 264 199 None 37 212 255 0. 23 None 39 233 .245 0. 04 36 202 260 0.69 None 36 231 168 None 36 208 266 0. 25 N one 37 236 362 (oH2),0H 3.7 None 37 222 240 0.22 None 35 246 1237 J (CH2)11CH= 7.0 0. 35 214 226 0.34 None 35 234 135 l (2-111ercaptoacetamido)methylcellulose prepared by the method of Example 8.

Example 15 The procedure of Example 14 was repeated four times, except that each time a different l-iodoalkane was used The introduction of hydrophobic alkyl groups by the methods described in Examples 14-16 permits the production of a water repellant cellulose derivative. If an alkylene dihalide is substituted for the alkyl halides one in place of iodoethane. The following derivatives in fabric can form a permanently cross-linked product.

17 18 Example 17 TABLE XVI Two samples of plain Weave cotton fabric (commonly Treating Solution known as 80 X 80 print cloth), were treated with disulfide Percent produced as described in Example 1. The disulfide was P t h d ami e Hi h Pereelng P t v811391! 001 l B e e e 8 dissolved in a 1.1 by weight dimethylformamide-water a Sample disulfide y r 3a, Step E g l g g f solution which also contained magnesium chloride to pro- I vide acidic conditions. The magnesium chloride was g- 2:; 3:3 3:; 22 added in the form of a buffered 30% aqueous solution (Commerclany avallable under h name Afirotex Crease recovery data on samples C and D are set forth celerator MX, sold by the American Cyanamrd Co.). In 10 in Table XVIL Table XIV, the figures under the heading percent MgCl I Soln. refer to the weight percent of Aerotex Accelera- TABLE XVI tor MX used in the treating solution. Crease recovery (W+F) (degrees) The fabric samples were impregnated with the solution sample Dry Wet using a laboratory padder and setting the rolls at a pres- 10 C 6 241 Sure to give Wet P p D'IIIIIIIIIIIIIIIII: 342 233 The fabric samples so treated were framed to the original dimensions, and dried at 60 C., then heated to Example 19 163 C. for 4 minutes in a forced draft oven. The fabric 9 samples were rinsed in a 1:1 dimethylformamide-water pl of 30 X 30 PTlIltclOth 0f the Same yp l mixture, then washed with an aqueous solution of a non- P y 1H EXamPle 3 Were f fi With the 3,3'-dlthl0bls ionic detergent. The samples were then framed and dried. y y y proplonamldel Producfid Table XIV below sets forth various data relating to scribed in Example 1- e reagent Was Padded the fabric samples A and B. fabric from a solution composed of dimethylformamide TABLE XIV Treating solution Percent Percent Percent weight Percent Sample disulfide lWIgClg Soln. increase yield Percent S Percent N S/N Act. S/N Theor.

The column headed Percent Disulfide and Percent r and water (2:1 by weight) which contained magnesium MgCl contains the wei ht ercent of the listed material chloride MgCl based on the weight of the reagent).

h l d gp lA dB Th Hfh dbh 'd(74 d38b int c so utions use to treat samp es an e p o t e pa at was varie an y The column headed Percent Weight Increase indimeans of dilute acetic acid). After padding, the fabric cates the increase in weight of the finished sample as comsamples were framed to the original dimensions, dried, pared to tlhe weight prior to treatmenlt. 40 cuigled1 (SdmiIrDmteS at1 l0 C.)t,hw2;sl';)edthorou1ghly, frarctiiei, The co umn headed Percent Yie d is an indication an rie ata re atmg to e a ric samp es treate y of the proportion of the disulfide reactant employed which this technique of padding and acid-catalyzed curing are reacts with the sample. summarized in Table XVIII.

The columns headed Percent S and Percent N set ABLE XVIII forth the weight percent of sulfur and nitrogen contalned T in the cloth samples after treatment. FY P d R t, yr r n The column headed S/N Actual is the ratio of the Built p eig i t, l eliri, za iimi, weight percent sulfur from the column headed Percent sample PH OWF Percent Percent Percent S divided by the weight percent nitrogen as set forth in ,4 4 g the column headed Percent N. 70

The column headed S/ N Theor. is the weight ratio Found by analysis (W+F) crease of sulfur to nitrogen 1n the disulfide reactant used in the recovery angle, a n 1 Bound degrees tensile samp 8.. N, S, CHZO strength, The samples were then tested for crease recovery Sample Percent Percent perflent y t p ds against a control which was the same weave fabric as A Q87 1,53 0,94 256 258 45 samples A and B wlthout any treatment. The results are B 95 273 8 3 summarized in Table XV.

TABLE XV Example 20 Crease recovery xv-pp (degrees) I Cotton samples E, F and G, which were previously 60 treated accordim to the procedure of Example 17 were s 1 w t amp 6 e padded with 0.5 molar aqueous ammonium thioglycollate gig (ATG) solution (pH adjusted to 9.0 by addition of am- 142 147 monium hydroxide) using a laboratory padder and setting Example 18 the rolls at a pressure to give 100% wet pickup. The fabric samples so treated were framed and dried at 60 C., then heated to C. for 2 minutes in a forced draft oven. The samples were rinsed in dilute acetic acid solution, then in water, finally framed and dried at 60 C.

A portion of each of samples E, F and G was then immersed for 5 hours in a 0.05 N iodine solution hulfered to pH 7. After this period of immersion the samples were rinsed first in water, then in 3% sodium thiosulfate solution for 1 hour, and finally in water. The portions were then framed and dried at 60 C.

The ATG treatment Was intended to show the reversibility of the disulfide linkages by conversion to mercapto groups. Table XIX indicates for samples E, F and G, the mercapto content after ATG treatment. The iodine treatment was intended to oxidize the mercapto radicals and convert them to disulfide, thus reversing the character of the sulfur portion of the reactant. Table I indicates that the iodine treatment lowered the percentage of mercapto radicals in the fabric, as expected.

different materials were used to provide acidic condi tions-the magnesium chloride used in Example 17 and the amine hydrochloride used in Example 18.

The samples were impregnated using a laboratory padder and setting the rolls ata pressure to give 95100% wet pick-up.

The fabric samples so treated were framed to the original size, dried at 60 C. and heated to 160 C. for 4 minutes in a forced draft oven. The samples were rinsed in a 1:1 dimethylformamide-water mixture and washed with non-ionic detergent. The samples were then framed TABLE XIX to original dimensions and dried.

Percent mercapto content Table XXII shows data obtained on samples treated Sample After ATG After Iodine w1th a solution containing 6.0% of a commercial buffered magnesium chloride solution. 1. 42 0. 59 1.02 0. 33 TABLE XXII 0 Percent Crease recovery disulfide Percent (W+F) (degrees) 8 1 in s0 luweight Percerllg -m The effects of the ATG and iodine treatments on the ampe Increase yw Dry 6 o sam les E F and are shown in I 6.0 2.2 44 257 m7 crease recovery f P G J 120 4'1 42 264 Table XX.

TABLE XX Crease recovery (W+F) (degrees) Before ATG treatment After ATG treatment After iodine treatment Percent weight Dry Wet Dry Wet Dry Wet increase Example 21 Example 20 was repeated on sample H to provide a 5.0% weight increase. However, instead of using iodine for the oxidation, the sample was exposed to humid air (65 F., 70% RH), after the ATG treatment. Table XXI shows crease recovery measurements made on sample H.

TABLE XXI Crease recovery (W+F) (degrees) Dry Wet Before ATG treatment After ATG treatment, immediately 198 216 After 24 hours 229 234 After 48 hours 236 232 From the increase in crease recovery, it is apparent that humid air is sufficient to reoxidize the mercapto groups formed during the ATG treatment.

Table XXIH shows data obtained on samples treated with a solution containing 3.0% of a commercial amine hydrochloride solution.

TABLE XXIII Percent Crease recovery disulfide Percent (W-t-F) (degrees) in soluweight Percent tion increase yield Dry Wet An untreated control had a dry crease recovery (W-i-F. degrees) of 195 and a wet crease recovery of 165.

Example 23 Rayon challis samples N and P, which were previously treated according to Example 22, were padded with 0.5 molar ammonium thioglycollate (ATG) solution (pH adjusted to 9.0 by addition of ammonium hydroxide), using a laboratory padder and setting the rolls at a pressure to give 90-100% wet pickup. The fabric samples so treated were framed to the original size and dried at 60 C., then heated to 150 C. for 2 minutes in a forced draft oven. The samples were rinsed in dilute acetic acid solution, then in water, finally framed and dried at C.

A portion of each sample was exposed to humid air F., RH).

60 Data obtained on the samples are set forth in Table XXIV.

TABLE XXIV Crease recovery (W+F) (degrees) Percent Before ATG treatment After 72 hours air After AT G treatment exposure welght Sample Increase Dry Wet Dry Wet Dry We t Example 22 Example 24 Viscose rayon fabric (commonly known as rayon challis) samples were treated with a disulfide produced as described in Example 1. The disulfide was dissolved in a M y w gh dirnc hy e ma ide-wa er solution. Two 7 The procedural details of Example 19 were followed. except that the reagent was dithiobis[N-(hydroxymethyl)acetamide and the actual pH values of the pad bath peroxide as per Example 15. Data on the products resulting from this series of reversible reactions are summarized in Table XXVIH.

TABLE XXVIII W+F Cr. recovery angle, deg. Warp tensile 5, Sample Form Dry Wet str., lb. percent percent C Mainly Thiol 203 231 30 i ulnde 230 269 31 o. 48 1. 33 E 'Ihlol 204 189 31 F Dlsulfide 229 269 33 TABLE XXV 15 Reagent Moisture Corr. Wt. Efliciency of Pad bath percent, regain, gain, utilization, Example 27 p OWF percent percent percent 6 19 6 1 7 8 48 The crosslmked product of Example 25 (sample B) 2.8 2.2 2% 0 Was treated with tetrakis(hydroxymethyl)phosphonium 316 1114 6.4 713 75 chloride using a procedure similar to that described in Found by analysis (W+F Creafe W Example 8. The product was characterized (as shown in recovery ang e, arp N fi g degrees tensillle Table XXIX) and then a portion of it was treated as de 2 strengt Sample percent percent percent Dry Wet pounds 25 scribed in Example with hydrogen peroxide. The re- 1 05 2 26 1 77 302 256 40 verslble cycle was repeated twice more. Data are sum- 1123 2172 2128 292 23s 34 marized in Table XXIX.

TABLE XXIX W+F Cr. recovery angle, deg. Warp tensile Total, Thiol, Sample Form Dry Wet str., lb. percent percent percent 13 Disulfide 266 280 32 0.55 1.92 None U 165 234 33 0. 40 0. 98 0.76 V- 243 25s 28 0. 54 1. 0. 14 w 164 210 33 0.62 225 251 30 0. 42 0. 93 None 167 224 28 0. Disulfide 226 243 28 0.43 0.88 None Example 25 Example 28 A sample of fabric resulting from treatment similar to that of Example 19 was immersed in 0.2-normal solution hydroxide for 30 minutes at room temperature with the fabric-to-liquor ratio at 1-to-30 by weight. Processing steps resembled those described in Example 4. The resulting product comprised mainly the thiol form with some pendant -CH NHCOOH CH SO H and --CH NHCOCH CH SO Na groups. Data are summarized in Table XXVI. Inasmuch as both reduced and oxidized forms of the starting material are formed, this cleavage of the disulfide is known as disproportionation.

A sample of cross-linked fabric resulting from treatment similar to that of Example 24 (sample A) was immersed in 0.2-normal sodium hydroxide for 30 minutes at room temperature with the fabric-to-liquor ratio at 1-t0-30 by weight to produce the predominantly thio form (sample B). Processing steps resembled those described in Example 4. Then the fabric was treated with hydrogen peroxide using conditions similar to those described in Example 5 (sample C). Then a portion of sample C was immersed in 0.2-normal sodium hydroxide according to the procedure described in Example 25, to give sample D,

TABLE XXVI Cr. recovery Warp angle, deg. tenstile Dry Wet 1b. percent percent ion 0 W a e e i h r i Example 26 a port f hlCh w s tr at d w th yd ogen perox de as per Example 5, to give sample B.

In another series, another sample resulting from treatment similar to that of Example 24 (sample G) was treated with tetrakis(hydroxymethyl)phosphonium chloride using a procedure similar to that described in Example 8 to produce the thiol form (sample H). Then a portion of it was treated in a manner similar to Example 5 with hydrogen peroxide to form cross-linked sample I. The reversible cycle repeated twice more (samples K-N).

Data on these two series of samples are summarized 1n The sulfur content of sample X after the treatment was Table XXX. 2.5%.

TABLE XXX W+F Cr. recovery 8 angle, degree Warp tensile N, Total Thiol, Dry Wet str., 1b. percent percent percent 289 229 38 0. 89 2. None 212 257 40 o. 45 251 280 36 0. 73 1. 53 0. 06 183 237 34 0. 23 239 255 31 None 289 229 38 0. 89 2. 25 None 194 230 39 0. 65 1. 68 1. 264 215 38 0. 60 1. 39 0. 41 186 229 38 0. 75 245 256 31 0. 55 l. 15 None 169 226 33 0. 58 N Disulfide 237 218 29 0. 44 0.24 None Example 29 Plain weave cotton samples (commonly known as 80 X 80 print cloth) were treated with a disulfide having the following formula:

The disulfide was dissolved in a 1:1 by weight ethanolwater solution containing magnesium chloride or amine hydrochloride, as described in the examples above.

The fabric samples were impregnated using a labora- CH-C Hrs] It is to be appreciated that the specific examples set forth above are intended to be illustrative of the present invention and variations may be made therein by one skilled in the art without departing from the spirit and scope of the present invention.

What is claimed is:

1. The method of modifying a material comprising cellulosic polymer molecules comprising the steps of providing an organic reactant embodying a first radical selected from the group consisting of a formyl radical, and an N-methylol amide radical or an ether derivative tory padder with the rolls set to provide 90l00% wet 30 thereof haVlIlg the following formula: pickup.

The padded samples were framed and dried at 60 C. Samples Q and R were then heated to 150 C. for 4 II I minutes in a forced draft oven. Samples S and T were C N CH2"OR treated to 176 C. for 4 minutes in a forced draft oven. 35 R" The samples were thoroughly rinsed and washed in dilute detergent solution and framed and dried.

Table XXXI sets forth data on samples treated with a solution containing 6.0% of the magnesium chloride where R and R" are selected from the group consisting of (a) a substituted 'or unsubstituted alkyl radical having from 1 to 4 carbon atoms and (b) hydrogen; said solution. 40 organic reactant also comprising a second radical selected TABLE XXXI from the group consisting of a mercapto radical in a free Percent disulfide Percent weight Percent S or protected form and a disulfide radical; said first radi- Sample insolution increase actual cal being separated from said second radical by at least Q M 0.6 one carbon atom; and heating said material with said R 15.0 1.1 0.33 organic reactant in the presence of an acidic catalyst at Table XXXII sets forth data on samples treated with a solution containing 3.0% of an amine hydrochloride solution.

TABLE XXXII Percent disulfide Percent weight Percent S Sample insolution increase actual SC0l1d radical by a substituted or unsubstituted alkylene s 5.0 1 (135 radical av ng from 1 to 4 carbon atoms, T 15.0 1.5 0. 43 3. The method of claim 2 in which said first radical is separated from said second radical by an alkylene radi- E l 20 cal having from 1 to 4 carbon atoms, said alkylene radi- The general procedure of Example 29 was repeated on cotton samples U, V, W and X. However, in this example, a 10% by weight aqueous solution of 2-thioglyceraldehyde was used. For samples U and V the solution also contained 5.0% of magnesium chloride solution as used in Example 17, and for samples W and X the solution contained 2.0% of the amine hydrochloride solution used in Example 18.

The data obtained on samples U, V, W and X are set forth in Table XXXIII below:

TABLE XXXIII Crease recovery (W+F) (degrees) cal comprising at least one oxygen atom.

4. The method of claim 2 in which said first radical is in the form of an aldehyde acetal radical.

5. The method of claim 2 in which said second radical is in the form of an S-acyl group. 6. The method of claim 1 wherein said second radical is mercapto.

7. The method of claim 6 wherein said mercapto radical is protected in the form of an S-acyl group.

8. The method of claim 1 wherein said second radical is a disulfide radical.

9. The method of claim 8 wherein said organic reactant is symmetrical about said disulfide radical.

Percent weight Percent .0 10. The method of claim 2 wherein said first radical Sample increase yield Dry Wet 1s formyl radlcal- 4.0 51 236 186 11. The method of claim 10 wherein said formyl is 53 3 237 182 in the form of an aldehyde acetal group. a: 12. The method of claim 2 wherein said first radical is said N-methylol amide radical.

13. The method of claim 1 wherein said organic reactant has the following formula:

[HO-OHrNH-(i-(CHQz-Sl 14. The method of claim 1 wherein said organic reactant has the following formula:

I CH OCHCH s a e 1. 15. The method of claim 1 wherein said reactant has the following formula:

HOCHzNHCCHzS- .L 16. The method of claim 1 wherein said reactant has the following formula:

II HO CHzNHtilCHzSC CH3 17. The product of the method of claim 1.

18. A cross-linked product of claim 17.

19. A un-cross-linked product of claim 17 20. A modified cellulosic material comprising cellulosic polymer molecules which are crosslinked through disulfide-containing linkages of the formula:

wherein R is hydrogen or substituted or unsubstituted alkyl radical of from 1 to 4 carbon atoms and T is substituted or unsubstituted alkylene radical of 1 to 4 carbon atoms.

22. A modified material according to claim 21 wherein said mercapto group is protected in the form of an S-acyl group.

23. The process of producing a cross-linked modified cellulosic material which comprises subjecting the product of claim 21 to oxidizing conditions.

24. The process of producing an un-cross-linked modified cellulosic material which comprises subjecting the product of claim 20 to reducing conditions.

25. The process of producing a modified cellulosic material which comprises reacting the material of claim 21 with an alkylation agent having an activated vinyl group.

26. The product of claim 25.

27. The modified cellulose of claim 21 wherein said mercapto group is in the form of an S-alkali metal group.

28. The method of modifying cellulose which comprises reacting the product of claim 27 with an alkyl halide.

29. The method of modifying cellulose which comprises reacting the product of claim 27 with an alkylene dihalide.

References Cited UNITED STATES PATENTS 3,102,773 9/1963 Needleman 8-116.3 3,160,469 12/1964 Vail et al. 8116.3 3,338,883 8/1967 Tesoro et a1 2602l2 OTHER REFERENCES Schwenker et al., Textile 'Research Journal, vol. 32, pp. 797-804.

DONALD E. CZAJ A, Primary Examiner R. W. GRIFFIN, Assistant Examiner U.S. Cl. X.'R. 

